The Polish resistance mounted an offensive against Nazi Germany – but hundreds of thousands were murdered in mass executions

The banner, which also had a Polish flag and the year 1944 in the background, was to mark the 73rd anniversary of the Warsaw Uprising, a key event in the war in Europe in World War II.

Legia also held a minute’s silence before kick-off.

The Warsaw Uprising began on August 1, 1944, and saw Polish resistance forces attempt to drive the Nazi army out of the city as Soviet forces arrived from the East.

But after 63 days – as Soviet leader Josef Stalin withheld troops in the hope the city would fall – hundreds of thousands were killed, mostly in mass executions by the Nazis and large parts of the city were completely destroyed.

Legia eventually beat Kazakh side Astana 1-0, although they were knocked out of the Champions League because of a 3-1 loss in the first leg.

The club, however, are likely to face an investigation by Uefa for the banner.